1. Field of the Invention
The present invention relates to a sound box structure. More particularly, the present invention relates to a sound box structure capable of immediately adjusting the effective volume of a sound box.
2. Description of the Related Art
A sound box structure generally comprises a casing and a speaker installed in the casing. The speaker is used for transforming an electrical signal into structural vibration to generate sound. The sound quality of the sound box structure is not only related to the speaker itself but also extremely related to the casing of the speaker. Generally speaking, a sound chamber in the sound box structure with a greater volume will reduce the damping effect of the air inside the sound box structure on the sound produced by the speaker. In such manner, the lowest resonant frequency of the speaker can be lower, thereby achieving a better low frequency response effect and thus improving the sound quality of the sound box structure.
As mentioned above, the low frequency response of the speaker is reliant on the internal volume of the box structure. In order to have better low frequency extension, a larger speaker has to be used. However, in a relatively small electronic device, such as a mobile phone, the size of the overall device has certain limitations. Therefore the effective volume of the speaker sound box is reduced, which accordingly raises the low frequency resonant frequency of the speaker sound box. The increase in the low frequency resonant frequency of the speaker sound box will degrade the low-pitched sound performance of the speaker and increase the distortion of the speaker, thereby influencing the sound quality of the mobile phone.
Therefore, there is a need to provide a sound box structure to mitigate and/or obviate the aforementioned problems.